1. Technical Field
The present invention relates generally to ovens for industrial baking applications and, more particularly, to a rigid oven module having expansion joints located intermediate to its ends for accommodating longitudinal thermal expansion in the module.
2. Discussion
For the past 10 to 15 years, modular baking ovens have been employed in numerous manufacturing environments for a variety of industrial baking applications, such as the baking of paint or another coating that is applied to any of an assortment of manufactured articles, including automobile bodies and components. Modular ovens are generally manufactured in sections or modules which are subsequently shipped to the place of use. The individual oven modules are then connected, in series, to form an oven baking line. Individual oven modules may be between 20 and 40 feet long and their layout may be varied depending upon the available floor space at the location of use. For example, a single pass oven baking line may include as many as 14 or more modules and extend to upwards of 500 feet or more. Whereas the same number of modules may be employed in a double pass oven baking line extending only, for example, 250 feet.
Typically, modular ovens include fabricated metal thermal expansion joints which are used to accommodate the longitudinal thermal expansion that occurs in the interior wall surfaces of the oven modules during their operation. These expansion joints are generally located at the ends of each oven module and are installed during the final assembly of the individual oven modules into the oven baking line. These expansion joints are also intended to create a seal at the ends of adjoining oven modules after they have been assembled in series, to prevent the escape of any gases from within the oven during operation. However, there have been several difficulties associated with this type of expansion joint. For example, because the thermal expansion joints are located at the ends of each individual oven module, both ends of the module are free to move when subjected to the forces of thermal expansion. Such movement can often result in significant overall dislocation of the oven modules along the entire baking line. Further, structural damage to the thermal expansion joint, which has been known to occur during the shipment and assembly of the oven modules, often cannot be corrected during the connection of adjoining oven modules and, consequently, the installation of the thermal expansion joints may often be difficult and unpredictable. Also, damaged thermal expansion joints can cause leaks of gases from the oven module during operation, thereby resulting in an undesirable environmental hazard. Still another undesirable design feature of the conventional oven modules described above is that the interior walls of these modules, which experience the greatest amount of the thermal expansion, serve to structurally support the module. Consequently, rebracing of the oven module is often required after periods of use.
Previous efforts to alleviate the above conditions have included attempts to design and construct a modular oven that includes thermal expansion joints located at or near the middle of the oven module as opposed to at its ends. However, these attempts have not proved successful and have resulted in modular ovens with unacceptably flimsy structures that were very susceptible to damage during shipping and assembly and which were difficult to install on site.
Explosion relief is another feature typical of oven modules. Conventional oven modules have included explosion relief simply by incorporating a gravity seal between the roof section and walls of the module. That is, the roof section of the module simply rests upon the walls, and by its own weight effectuates a seal at the edges where it meets the walls of the module which may be "blown" in the event of an explosion in the oven module. In this configuration, however, the roof does not contribute to the structural rigidity of the oven module.
In view of the above, it has been considered desirable to provide an oven module for industrial baking applications that is capable of accommodating the longitudinal thermal expansion that is experienced in the oven module, yet is easy to ship and assemble and also exhibits increased structural rigidity over prior known oven modules.